/* roulang page: index */
:root {
      --primary-bg: #0A0E27;
      --accent-cyan: #00E5FF;
      --gold: #FFB800;
      --card-bg: rgba(20, 30, 60, 0.55);
      --card-border: rgba(0, 229, 255, 0.15);
      --text-primary: #FFFFFF;
      --text-secondary: #B0C4DE;
      --text-muted: #6B7FA3;
      --shadow-glow: 0 0 20px rgba(0, 229, 255, 0.4);
      --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.5);
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: 'Inter', "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
      background-color: var(--primary-bg);
      color: var(--text-secondary);
      line-height: 1.75;
      margin: 0;
      scroll-behavior: smooth;
      -webkit-font-smoothing: antialiased;
    }

    .glass-card {
      background: var(--card-bg);
      backdrop-filter: blur(16px);
      -webkit-backdrop-filter: blur(16px);
      border: 1px solid var(--card-border);
      border-radius: 1.5rem;
      box-shadow: var(--shadow-card);
      transition: all 0.3s ease;
    }

    .glass-card:hover {
      box-shadow: 0 0 28px rgba(0, 229, 255, 0.3), 0 8px 32px rgba(0, 0, 0, 0.6);
      border-color: rgba(0, 229, 255, 0.35);
      transform: translateY(-4px);
    }

    .number-font {
      font-family: "DIN Alternate", "SF Mono", "Menlo", monospace;
      font-weight: 700;
      letter-spacing: 0.02em;
    }

    .text-glow-cyan {
      color: var(--accent-cyan);
      text-shadow: 0 0 15px rgba(0, 229, 255, 0.5);
    }

    .btn-primary {
      background: var(--accent-cyan);
      color: #0A0E27;
      font-weight: 700;
      border-radius: 0.75rem;
      padding: 0.85rem 2.2rem;
      transition: all 0.2s ease;
      box-shadow: 0 4px 14px rgba(0, 229, 255, 0.25);
      border: none;
      letter-spacing: 0.02em;
      display: inline-flex;
      align-items: center;
      justify-content: center;
    }

    .btn-primary:hover {
      box-shadow: 0 0 30px rgba(0, 229, 255, 0.7);
      transform: translateY(-2px);
      background: #26EAFF;
      color: #050A1F;
    }

    .btn-outline {
      border: 1.5px solid var(--accent-cyan);
      color: var(--accent-cyan);
      background: transparent;
      font-weight: 600;
      border-radius: 0.75rem;
      padding: 0.85rem 2.2rem;
      transition: all 0.2s ease;
      backdrop-filter: blur(8px);
      letter-spacing: 0.02em;
    }

    .btn-outline:hover {
      background: rgba(0, 229, 255, 0.12);
      box-shadow: 0 0 22px rgba(0, 229, 255, 0.45);
      transform: translateY(-2px);
    }

    .nav-link {
      color: var(--text-secondary);
      font-weight: 500;
      font-size: 0.95rem;
      transition: color 0.2s, text-shadow 0.2s;
      position: relative;
    }

    .nav-link:hover {
      color: var(--accent-cyan);
      text-shadow: 0 0 8px rgba(0, 229, 255, 0.5);
    }

    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -6px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--accent-cyan);
      box-shadow: 0 0 12px var(--accent-cyan);
      transition: width 0.25s ease;
    }

    .nav-link:hover::after {
      width: 100%;
    }

    .hamburger-line {
      display: block;
      width: 24px;
      height: 2px;
      background: var(--accent-cyan);
      margin: 5px 0;
      transition: 0.3s;
    }

    .accordion-content {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease-in-out, padding 0.2s;
    }

    .accordion-open .accordion-content {
      max-height: 300px;
      padding-top: 1rem;
    }

    footer a {
      color: var(--text-muted);
      transition: color 0.2s;
    }

    footer a:hover {
      color: var(--accent-cyan);
    }

    @media (max-width: 768px) {
      .glass-card {
        border-radius: 1rem;
      }
      h1 {
        font-size: 2.2rem !important;
      }
      h2 {
        font-size: 1.7rem !important;
      }
    }

    .bg-grid {
      background-image: radial-gradient(rgba(0, 229, 255, 0.08) 1px, transparent 1px);
      background-size: 40px 40px;
    }